Evaluation and Pilot Testing of a Direct Turbo Dryer at a 5.0 MGD Facility. Brandon Gott

Transcription

1 Evaluation and Pilot Testing of a Direct Turbo Dryer at a 5.0 MGD Facility Brandon Gott

2 Agenda Background EPA regulations Project drivers Pilot goals & objectives Pilot Unit Tests Sampling Dryer modifications Results Product Odors

3 Background Westminster WWTP located in Carroll County, Maryland Operated by City of Westminster ENR Upgrade to include a new Biosolids Processing Facility ENR Class A study evaluation completed in 2010: Thermal Dryer selected Project location

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5 US EPA, 40 CFR Part 503 Rule Per US EPA Part 503, in Class A biosolids, it must not only meet, but exceed, all Class A pathogen and vector reduction requirements as specified in. Various processes can be utilized to achieve this Class A designation, such as anaerobic digestion, lime stabilization, composting, or thermal drying Thermal Drying Process accepted as a process to significantly reduce pathogens to produce Class A. Must meet the following: 1. 90% dried solids Dried Solids %Target 2. Temperature of biosolids material or wet bulb temp of gas in contact with material be 176 F (80 C)

6 Project drivers ENR design project Existing municipal dryers Dryer operational & maintenance concerns Safety hazards (dust & smoldering) Construction startup Odors WYSE direct turbo dryer pilot Reported less odors and dust Operates at lower temperatures Not proven in municipal market

7 Direct dryer pilot goals and objectives 1. Characterize physical and chemical properties of the dried biosolids 2. Evaluate dried biosolids for end uses (92%) and compliance with Federal/State regulations (90%) 3. Evaluate dryer operation using plant s dewatered biosolids 4. Familiarize plant staff with the direct dryer 5. Characterize odor emissions to evaluate odor control requirements

8 Direct dryer pilot unit Parameter Model Height Diameter Footprint (LxW) Evaporation rate Inlet screw feed rate Air flow Air burner Fuel source Value LHT-17 (17 trays) (w/feeder) 7 ft 20 ft x 15 ft ~80 lbs/hr 100 lbs/hr 1,000 ACFM 400,000 BTU/hr Propane

9 Direct dryer pilot

10 Direct dryer pilot schematic

11 Direct Dryer pilot

12 Direct dryer on-site pilot testing Pilot testing period May thru July 2014 Manufacturer onsite for setup and start-up Pilot operated by City personnel City collected samples and performed testing Sampling/testing approach City sample collection and testing Pilot test/sampling protocol Testing schedule

13 Dryer sampling/testing protocol Recommended Loading Time prior to Beginning Testing (1.5 times the retention time or 240 minutes) Loading Time 240 minutes Provided by Mfgr 4 hrs Loading Time = 1.5 x retention time = 4 hrs 14% DS 15% DS 16% DS 17% DS Est. Retention Time, min to achieve 90% Solids Estimated Retention Time 120 minutes 2.00 hrs Time Load Dryer Record/Sample Input Collect/Sample Biosolids Dispose of Dried Product 8:00 AM 9:00 AM 10:00 AM 11:00 AM 12:00 PM 1 1:00 PM 2:00 PM 2 1 3:00 PM 4:00 PM 3 2 5:00 PM 6:00 PM 4 3 7:00 PM 8:00 PM 5 4 9:00 PM 10:00 PM :00 PM 12:00 AM 7 6 1:00 AM 2:00 AM 8 7 3:00 AM 4:00 AM 9 8

14 Direct dryer pilot initial testing (May-June 2014) Dryer set points Top damper - 20% open Middle damper - 90% open Bottom damper controlled by bottom temp Feed - 90 to % DS (avg) Dryer temperature F to 325 F Retention time 80 to 140 min

15 Direct dryer pilot testing (May-June 2014) Initial results Dried product was granular and lumps Dried product solids: 50% to 99.4% Significant heat loss between burner and dryer Evaporative capacity: 81 lbs/hr (avg) Exhaust air temp: 86 F to 127 F Thermal efficiency: 2,200 BTUs/lb

16 Direct dryer pilot modifications Rotocage Lumpbreaker installed Increased % of recirculated air reduce fresh air Reduced top damper opening Two new trays: Expanded metal frame for semi-dry material Radial Wires across material movement for semi-wet material Modified plow wiper (1/8 clearance) Installed spill baffles Higher turndown ratio on feeder drive/gear Adjusted retention time Insulated manifold & pipe

17 Direct dryer pilot testing (June 2014 July 2014) Dryer set points Top damper closed Middle damper at 50% open Dryer Set Points: 285 F to 300 F Feed: 65 to % DS (avg) Retention Time: 120 to 160 min

18 Direct dryer pilot testing (June 2014 July 2014) Results Granular coarse material Smaller (walnut) size lumps: 55% to 85% DS Pea size material: 92% to 99% DS Evaporative Capacity: 88 lbs/hr (avg) Exhaust air temp: 102 F to 184 F Thermal efficiency: 1,700 BTU/lb Dried product temperature: 200 F

19 Direct dryer pilot results Wet Feed Cake Solids Temperature Setpoint Retention Time Dried Product % Solids Dried Solids, % / Temperature, F / Time, min Initial Testing Dryer Modifications Final Testing 92% Test Runs

20 Dried product size EPA Target % DS: 90% DS End User Product Targets Particle Size: ~6 mm BTU Heating Value: >5,500 BTU % Dried Solids: 88 90% DS Two-deck round vibratory separator Dried Product 108 lbs Top Deck 7/16 mesh (11.2 mm) Bottom Deck ¼ mesh (6.35 mm) Results Top deck screen captured 9% Bottom deck screen captured 45% 45% went straight thru 91% of all material > 92% DS

21 Compound A. Sulfur Compounds Odor Threshold, ppb Avg. Concentration, ppb Indirect Direct Hydrogen sulfide 0.4 1,162 <5 Methyl mercaptan ,210 <7 Dimethyl sulfide <1.3 Dimethyl disulfide 2.2 1,089 <1.8 Dimethyl trisulfide <0.1 B. Nitrogen Compounds Trimethylamine Ammonia 5 ppm 2 ppm 4 ppm C. Aldehydes Propanal <0.5 2-methyl propanal? 1,856 <0.1 3-methyl butanal <0.1 Hexanal 1 84 <0.3 Decanal <0.1 Total aldehydes - 2,530 <8 D. Fatty Acids N-butyric acid <0.1 Propyl 2-methyl butanoate? 34 <0.1

22 Direct dryer summary results Operation compliant with Federal/State Regulations Dried Product Dried Material Product (200 F) 90% > 90% DS achieved at 275+F Reduced odor concentrations BTU Heating Value: 7,420 BTU/lb Sludge Smoldering Test: >450F Recycle needed for 9% of dried material Thermal Efficiency Final Pilot Thermal Efficiency: 1,700 BTU/lb Industrial Industry: 1,500 BTU/lb Typical Municipal Thermal Efficiency Range: (1,200 to 1,600 BTU/lb) Bacteria Fecal, Bacteria, Coliform: <0.18 MPN/gram dry weight

23 Project status

24 Acknowledgements City of Westminster Jeff Glass, John Rawlings, Vance Summerhill, Mark Mellendick Wyse Dryer manufacturer representatives Jack Granas, Rich Koch, Vladimir Godovich

25 Questions?